Dear Sir: In his interesting article on "Spontaneous Movements in Plants," printed in your January number, Dr. A. W. Bennett remarks, page 284, that "the selective power of plants, in absorbing from the soil a larger portion of those ingredients which are required for the formation or healthy life of their tissues, is an absolutely unexplained phenomenon." Dr. Bennett says further, "A striking instance of the liability to consider a mere statement of an obscure law in other terms as an explanation of that law, occurs in an admirable treatise on the growth of plants—Johnson's 'How Crops Grow.'" Then follows the subjoined quotation from my book (the italics are Dr. Bennett's): "The cereals are able to dispose of silica by giving it a place in the cuticular cells: the leguminous crops, on the other hand, cannot remove it from their juices; the latter remain saturated, and thus further diffusion of silica from without becomes impossible, except as room is made by new growth. It is in this way that we have a rational and adequate explanation of the selective power of the plant." Dr. Bennett adds: "The 'rational and adequate explanation' seems to me, on the contrary, to be merely a restatement of the selective power of the tissues in other terms. Because the tissues want the silica, is no explanation of how they get it."

Very possibly, Dr. Bennett holds me at a disadvantage as the matter thus stands, but I am, in fact, very seriously misrepresented in the last sentence of his quotation from "How Crops Grow." On page 363 of the American edition, the reader may see that the period which concludes Dr. Bennett's quotation should be a comma, and that the sentence, as I wrote it, first comes to a conclusion after an important qualifying clause, and reads, entire, as follows:" It is in this way that we have a rational and adequate explanation of the selective power of the plant as manifested in its deportment toward the medium that invests its roots."

It appears that Dr. Bennett has inadvertently confused two quite distinct things. He asserts, at first, that "the absolutely unexplained phenomenon" is "the selective power of plants in absorbing from the soil those ingredients which are required for their tissues." But, afterward, he declares my "explanation" to be "merely a restatement of the selective power of the tissues." Obviously, the selective power of the plant, as manifested toward the medium that invests its roots, is one thing, and the selective power of the tissues toward the substances dissolved in the cell-juices is, or in many cases may be, another. The former is what I offered a rational and adequate explanation of. The latter I have not ventured to attempt to explain. The former is explained by being coordinated with the well-ascertained facts of "diffusion" and "osmose," and referred to established, if not fully-developed, physical laws. The latter belongs to the yet very obscure phenomena of chemism, which are only known to us imperfectly in some of their results, and whose inner nature the recent amazing progress of organic chemistry has hardly begun to enable us to speculate upon with any satisfactory degree of probability.

Dr. Bennett writes of silica as one "of those ingredients which are required for the formation or healthy life" of the plant-tissues. In "How Crops Grow," the evidence is given which forces us to the conclusion that silica is unessential to the growth and perfect development not only of leguminous plants, but of all the various cereals, although the latter, when they grow in the soil, do contain 2.5 per cent., more or less, of this substance in their foliage. If silica be taken up by legumes and by corn-crops which are able to grow to perfection of parts and fulness of dimensions in its absence, then, certainly, "because the tissues want silica is no explanation of how they get it;" but saturation of the cell-juices does explain how a limit is put to the influx of this body into the plant from the soil.

S. W. Johnson.

Probable Cause of Boiler-Explosions.—Some six years ago, Mr. W. F. Barrett, F.C.S., observed that a red-hot ball of copper, on being immersed in a light solution of soap in water, entered the liquid without hissing or visible generation of steam. In a paper read before the British Association, he tells of sundry experiments, made with a view to investigate this phenomenon, and thinks that it probably accounts for many otherwise unaccountable explosions of steam-boilers. After experimenting with sundry red-hot metals in soap-water, he tried water without soap; but then the hissing was loud, and the evolution of steam copious. He next dissolved in water several soluble substances, and found that albumen, glycerine, and organic liquids in general, facilitate the acquisition by water of the spheroidal shape, probably by increasing its cohesion, while bodies such as ammonia, which yield vapor readily, have the same effect, though in not so marked a degree. Oil, whether shaken up or floating on the water, has the same effect as soap. When the red-hot ball is lowered into the liquid, to a depth of a foot or more, it is seen to be surrounded by a shell, of vapor, bounded by an envelop resembling burnished silver. As the ball cools, the shell grows thinner, and finally collapses. This is followed by a report, and volumes of steam are emitted. The author adds: "I have heard that traces of oil get into the boilers of steam-engines, and there can be no doubt that dissolved organic matter often finds its way in. If in any way we increase the intensity of the water, we render it possible for a corroded boiler to give way under the pressure of the steam suddenly generated in the way I have indicated."

Practical Application of Singing Flames.—The "singing flame," which at first view might seem to be merely a curious phenomenon, is found to be, in fact, a discovery of very high importance for science and the useful arts. One of the latest applications of this principle is that made by Dr. A. K. Irvine, of the British Iron and Steel Institute, who makes use of the singing flame in the construction of a safety-lamp for mines. If an explosive mixture of inflammable gas and air be passed through and ignited on the surface of a disk of wire gauze too fine to suffer the flame to traverse it, and then surrounded by a chimney, to prevent air from entering, save through the gauze, the flame vibrates, and, the vibration being communicated to the ascending gases, produces a sound varying in pitch and intensity according to the height and calibre of the chimney. A lamp constructed on this principle will give timely warning to the miner whenever the atmosphere and the fire-damp are coming together in the proportions requisite for an explosion.

Science in the Household.—The application of science to the affairs of the household, both in the shape of improved processes and the introduction of labor-saving appliances, has already gone sufficiently far to warrant the expectation that from this quarter there will eventually come a solution of the problem of rational house-keeping, when the family will be largely rid of the annoyances incident to a state of dependence on incompetent and wasteful hirelings, and master of its own internal economy. Already the sewing-machine has wrought a revolution in the clothing department, which leaves scarcely a trace of its former wearisome tasks. The washing-machine and wringer, aided by various detergent preparations, have in like manner greatly lightened the work of the laundry, making the destructive and exhausting labor of rubbing a useless waste of power. And now, as the latest and most important addition to the resources of the house-keeper, we have a device which, going under the name of the "Warren Cooker," accomplishes an even greater reduction in the labor, expense, and care of the culinary department of the household.

This implement was but recently introduced into this country, and, though widely commended, is comparatively unknown; we cannot, therefore, do our readers a better service than to give them a brief account of its advantages. The article is an application of the principle that cooking is best done at a low, uniform heat, or a heat that, in the case of meats, will neither coagulate their juices nor harden their fibre. By Warren's plan both meat and vegetables are cooked at the same time, though in separate compartments and in different ways. When the "Cooker" is in operation, the meat is enclosed in a tight chamber, the bottom of which rests in boiling water, while a large portion of the sides is surrounded by steam, the remaining or upper portion of the sides being exposed to the outer air. No water or steam is permitted to enter the chamber, which, by the above-described arrangement, is kept at a uniform temperature of about 210° Fahr. The juices of the meat, and consequently its flavor, are thus wholly retained without dilution or impairment, and at the end of the process both fibre and juices are left in a condition most favorable to the work of digestion, none of the hardness or stringiness of baked or roasted meats being in the least degree perceptible.

Vegetables are cooked by steam, which in its exit is made to traverse a chamber divided into compartments for the reception of different sorts. Dumplings, or any thing else permitting the direct contact of steam, may also be cooked in this part of the apparatus.

We have had the implement in almost daily use for upward of six months, cooking with it the meat, fish, and poultry, ordinarily employed for the table, and its general performance has been in the highest degree satisfactory. It saves all round, and might very appropriately have been named the "Economical Cooker." Compact and simple in arrangement, it is easily and quickly got into operation. Unable to go wrong when once properly started, it does away with the worry and care incident to ordinary cooking. Run by any contrivance that will boil water, it makes possible a great saving of fuel. Cooking the meat in a closed pot, without access of either water or steam, it saves over the old way a large percentage of material; and, always turning out an evenly-cooked, juicy, and never overdone joint, it above all saves the feelings of the entire family.

To this strong indorsement of the implement, it is our duty to add a word of caution, for the benefit of those who are just commencing its use. The circulars of the manufacturer state the time per pound required for cooking various meats. Rigidly adhering to these directions when we first began to use the "Cooker," underdone dinners were the frequent result; and it was soon learned that from three to five minutes additional per pound were required to make the process complete.

Not the least of the advantages that will follow the general adoption of this mode of cooking will be, the encouragement of simplicity in the preparation of food; for, inasmuch as the contrivance preserves the natural flavor of the articles cooked in it, there will be no need of adding all sorts of rich and indigestible sauces to replace the losses which occur in cooking by the methods now commonly employed.

Venomous Spiders in New Zealand.—Until recently it was supposed that New Zealand contained no venomous reptiles or noxious animals of any kind, and it was only so late as the year 1856 that the first scientific notice appeared of a poisonous spider, a native of that country. This notice was communicated to the British Linnæan society by Dr. Ralph, and contained a brief description of the katipo (night-stinger), giving an account of its nesting habits and of the potency of its sting. A writer in the Field, who has closely studied this animal in its native habitat, cites numerous instances showing that the katipo's bite is occasionally fatal, and invariably very painful. Like many other venomous creatures, the katipo is not aggressive, and stings only when he is molested and greatly irritated; but, if merely touched with the finger, he will fold up his legs, and feign death. If again molested, the animal will try to escape, and will employ his sting only when driven to the wall. The katipo's nest is a perfect sphere, and the eggs about the size of mustard-seed. The changes undergone by this animal in its progress toward maturity are as follows: In the very young state its body is white, with two linear series of connected black spots, and an intermediate line of pale red; under parts brown; legs light brown, with black joints. In the next stage, the forepart of the body is yellow, with two black "eye-spots," sides black, with transverse marks of yellowish white; dorsal stripe bright red, commencing higher up than in the adult, and with the edges serrated. At a more advanced age the stripe on the back is brighter, with a narrow border of yellow, and the thorax and legs are nearly black. In the fully adult condition, the female is very handsome in form and color. The body varies in size from that of a pigeon-shot to that of a small green pea; and the outspread legs even of the largest of these animals cover only a space of three-quarters of an inch. The thorax and body are black and shining, with a stripe of bright orange-red down the centre of the body. The male is considerably smaller, having the body blackish brown, with a faint-yellow line down the back.

Prof. Agassiz's Estimate of New-England Education.—The following significant paragraph is from the Tribune:

"Prof. Agassiz's speech before the Committee on Education at Boston, last week, was practical, impetuous, and a little impatient. His demand for a State appropriation for the benefit of the Cambridge Museum served as a text from which he drew a sermon, unpleasant, but not untrue nor unnecessary. He warmly expressed his disapproval of the existing system of popular education in America. Instead of using the rich and growing intellectual material of later years, he declared that our colleges teach chiefly the traditional learning of the middle ages. 'Harvard,' said the fiery professor, 'is not a university; it is only a tolerably well-organized high-school.' Nor is even this learning, in his eyes, the best of its kind; it is merely the dregs of scholarship. He brought up our grammar as an example, referring to it as no longer a living matter, but a reduction to formulas from which all the living spirit has fled. As for his darling, Natural Science, he contemplates mournfully the want of thoroughness with which its phenomena are taught in the common schools. The fault, he asserts, is that of the teachers, who have no sort of thorough knowledge in this direction, and who cannot get it from the normal schools, where instruction is given from text-books alone, and in the poorest possible manner. The schools of Massachusetts had round censure from the good professor, and very much it must have astonished the authorities of that great State, who are incessantly ready to fold their hands and go to heaven when they think of their 'superior' school system. Owing to the misplaced confidence which they have in it, the professor thinks that it might be easier to push a new course of education in a new State earlier than in New England."

Ancient Bavarian Agriculture.—The Historical Society of Munich has recently set on foot an investigation of the remains of ancient agriculture to be found in the neighborhood of that city, and in other parts of Bavaria. Garden-plots of an unknown antiquity have been discovered, many of them assuming the form of a parallelogram, with beds of equal length, breadth, and height; while others are in the form of a trapeze, with beds of very unequal length. Often-times wide and narrow beds alternate; and again beds are found side by side, the one being ten times the length of the other.

In height they vary from 1¼ to 3 feet or over, and the soil is scooped up out of the furrow and thrown up on the bed, uncovering the gravel. There is no trace of drains or water-courses dating from the period of these gardens, though water-courses of a later time are to be seen. In the middle of one of these agricultural districts is always found a free space where in all probability the people had their dwellings, although we find no trace of their abodes. If there ever were houses there, they must have been built of light material. Horseshoes are found at various depths in the soil. These are of small dimensions, and so eaten away by rust that they evidently belong to a very remote period. A writer in the Presse is of opinion that these little farms date back some 2,000 years, and that then the climate of Bavaria was very moist; for such treatment of the soil in the present comparatively dry climate of that country would lead to the destruction of the crops by drought. It is a little curious that the writer makes no mention of any agricultural or other implements being found; but perhaps closer investigation will bring such objects to light.

Recent Meteorites in France and Italy.—Several members of the French Academy of Sciences have written for that body accounts of two or three meteoric masses lately seen to fall in France and Italy. On July 23d, at about half-past five, on a still afternoon, with clear sky, and the sun shining brightly, there was heard at Lancé (Loir-et-Cher) a violent report, succeeded by a rumbling. A "fiery lance" was observed by a land-owner of Lile-Bouchard to shoot across the sky with great swiftness. En route it divided into two meteors, which continued for some time to move parallel. At Tours they were also observed, and described as bottle-shaped, and of an orange color. One of these meteorites was found near Lancé by M. de Tastes. It weighed about 103 lbs., and had penetrated into the earth to a depth of 5 feet 9 inches. It broke to pieces on removal. The other meteorite was soon after found, some 7½ miles south of the first. It was of the same character as the first, but weighed only a few ounces and had penetrated about 20 inches. The large piece is of an unequal spheroidal shape, with rounded surface, and covered with a crust as if by fusion. The fracture is black, showing globular structure, and numerous small spheroidal grains. Here and there are small metallic grains, yellow in color. Specific gravity 3.80. In water it yielded a very small quantity of chloride of sodium. There is not a trace of salts of potash, nor any sulphates or hyposulphates. Dissolved in nitric acid, a silicate was found, consisting chiefly of magnesium and protoxide of iron. Spectrum analysis seemed to indicate the presence of copper; but there was no calcium, barium, or strontium. Carbon was absent, but, as usual, cobalt and nickel accompanied the iron. On the evening of August 8th, at 8 minutes past 11, a meteorite was seen at Rome, Velletri, and other places. But a more interesting one was observed by Padre Secchi at Rome, August 31st, at 5.15 a. m., mean time. A globe of fire was observed, well marked and a little red in color. Its progress was at first slow, but it gained speed, and left behind it a luminous train like a cloud lit up by the sun. On reaching its highest point, it suddenly expanded, and finally disappeared. Three or four minutes afterward a tremendous detonation was heard. It was like a mine-explosion, and was followed by a rolling sound, as of file-firing. A fragment of this meteor was picked up and found to be very ferruginous, hard, and covered with a crust. The extreme distances at which the meteorite was seen are 93 miles apart.

An Efficacious Disinfectant.—A writer in the Chemical News offers some useful hints on disinfectants, which may be of interest. After a long-continued series of experiments, he pronounces sulphate of aluminium and hydrochlorate of alumina very powerful disinfectants and antiseptics. Their solubility and harmlessness render their use admissible under all ordinary circumstances. The chloride and sulphate of iron have the same action as the above, and, further, they absorb the sulphuretted products of decomposition. For this reason these salts are the most efficacious of disinfectants. But there is one objection to their use, viz., that the iron would injure any vegetation with which the disinfected matter might come in contact. The writer recommends, as the best of all disinfectants, for general use, a solution containing hydrochlorate of alumina, with a small quantity of chloride of iron. The hydrochlorate will do all the work of a disinfectant and antiseptic, while the chloride will absorb the sulphuretted compounds.

Atmospheric Pressure and Vegetable Growth.—M. Bert, whose observations upon atmospheric pressure and animal life we have already noted, has been making experiments upon the influence of pressure on vegetation. From these it would appear that temperature is not the only condition modifying vegetal growth at varying altitudes, but that varying degrees of atmospheric pressure have also a controlling influence in this respect. Some grains of wheat were sown in bell-glasses with all the conditions identical, save that the contents of one glass were subjected to the normal pressure of the atmosphere, those of another to two-thirds the ordinary atmospheric pressure, and those of a third to one third the ordinary atmospheric pressure. The first grains sent forth shoots 20 centimetres (7 inches) long, the second 5 inches, and the third did not come up at all. Again, with a pressure of 5 atmospheres, the plants did not come up, the radicles only having been sent out, and on opening the vase a strong alcoholic odor was perceived, in place of the ordinary acetic odor of putrefying wheat. After a few days a mould made its appearance.

Electric Detonators for exploding Mines.—Two new electric detonators, for exploding mines, one for land and the other for marine service, have been introduced in England. The former consists of a tin tube filled with fulminating mercury, and having a head of beech-wood. The electric wires run through this head, being insulated by gutta-percha, and their extremities held apart. In the space between the ends of the wires, and in contact with the fulminating mercury, is loosely packed a little gun-cotton, which is ignited by an electric current. The marine detonator has also a tube of tin filled with fulminating mercury, as also a beech-wood head. From tip to tip of the wires extends a platinum wire 3⁄10inch long, and 0.003 inch thick, in a bed of loose gun-cotton. The electric current heats the platinum, thus igniting the gun-cotton and exploding the fulminant, which in turn explodes the powder.

Development of Vibrio-Life.—In the course of his very interesting experiments on protoplasmic life, Dr. Grace Calvert shows that a solution of albumen from a new-laid egg, in pure distilled water, does not develop protoplasmic life, when the atmosphere is shut out. If, however, it be exposed to the atmosphere for from 15 to 45 minutes, minute globular bodies will appear, which have an independent motion. The time required for these bodies to develop is proportioned to the surface exposed, as was shown by Dr. Calvert, who experimented with two portions of albumen, 400 grains each, one in a test-tube of three-fourths inch diameter, and the other in a test-glass showing a surface of liquid two inches in diameter to the atmosphere. In the tube, vibrios appeared after twelve days, but in the glass after five. With undistilled water, they appeared in the test-tube within 24 hours. Further, M. Pasteur having shown oxygen to be necessary to the life of the mucedines, Dr. Calvert shows that it is no less necessary to the existence of vibrios. To confirm this, he put into each of five glass bulbs a solution of albumen in water, the first being left in contact with the atmosphere 24 hours, and the ends of the tube then hermetically sealed about two inches on each side of the bulb. The other tubes were similarly closed, after passing oxygen, hydrogen, nitrogen, and carbonic acid, over the solutions. The tubes remained closed for 27 days, during which period the albumen in contact with oxygen was seen speedily to become turbid, and then that in contact with air, while the other three remained clear. The tubes were then broken, and it was found that those containing oxygen and common air held a large amount of vibrio-life, while those containing nitrogen, carbonic acid, and hydrogen, held but very small quantities; hydrogen least of all. Thus it was proved that oxygen is an essential element to the production of putrefactive vibrios. The transition from globular protoplasms, or monads, as he calls them, into vibrios, and their ultimate transformation into microzyma, is then described by Dr. Calvert. "A few hours after impregnation," says he, "the monads appear in the albumen, having a diameter of about 1⁄128000 of an inch, and appear to form masses. Next, some of the monads are lengthened into vibrios, which have an independent motion, though still attached to the mass. As this motion prevails in this or in that direction, the mass is moved over the microscope-field. At last it is broken up, and soon each individual vibrio is seen rolling or swimming about. Their size is now 1⁄20000 of an inch, and they finally attain a length of 1⁄6400 of an inch." These long vibrios are gradually changed into cells, which Dr. Calvert calls mierozyms, the first step in transformation being their division into two independent bodies. An extremely faint line appears across the animalcule's centre, increasing in distinctness until the vibrio looks like two individuals joined together. Then they separate, acquiring each an independent existence. The parts again divide and subdivide, until they appear to be no more than cells endowed with great natatory power. In twelve months or so the vibrios disappear, being succeeded by mierozyms, either in motion or at rest. If these latter be placed in a solution of fresh albumen, vibrios are abundantly developed, apparently because they have now all the circumstances favorable to their growth and reproduction.

Experiments on the Circulation of the Frog.—Certain drugs, such as digitalis, veratrum, and ergot, when taken into the system, are known to exert a powerful influence on the apparatus of circulation, and, on this account, are largely employed by physicians as medicinal agents. In order to learn something further of the manner in which they act, Dr. Boldt has been studying the effects produced by their active principles when thrown into the circulation of the frog. Curarized frogs had the intestines and mesentery exposed, so that the movement of the blood in these parts could be readily watched through the microscope. Twelve experiments with digitalin, injected hypodermically, showed that it produces a strong contraction of the peripheral vessels, which is followed by a marked slowing of the pulse, and this, if the dose be large enough, by laming of the heart, as shown by smallness, irregularity, and rapidity of the pulse, with a vibrating or undulating blood-stream; finally, after a short increase in rapidity, the pulse falls with great suddenness, and then, with general vaso-motor paralysis, the animal dies. Eleven experiments with veratrin showed that it directly paralyzes heart and arterial muscles, there being an immediate lowering of the pulse-frequency, the size and force of its wave, and an increase in the lumen of the vessels. Twelve experiments with ergotin resulted in a constant lowering of the pulse-rapidity, by both large and small doses, accompanied by peristaltic or wave-like contractions and expansions of the artery.

Paper Car-Wheels.—Car-wheels of paper, though universally admitted to be superior to those of iron or steel, have not been much used hitherto, owing to their high price. If, however, as is claimed, paper wheels are more durable than those of other materials, and if they do less injury to the tracks, besides being safer and more noiseless, it may in the end be found economical to employ them. The Connecticut River Railroad, as we learn from the Iron Age, is about to give these wheels a practical trial, having ordered a set of them for the forward truck of a locomotive. The process of manufacturing wheels of paper is as follows: A number of sheets of common straw-paper are compacted together under a pressure of 350 tons. The mass is then turned perfectly round, and the hub forced into a hole in the centre. The tire, which is of steel, has a bevel of one-quarter of an inch on the inside edge, and the paper filling is forced in under a pressure of 250 tons. Two iron disks, one on either side, and bolted together, keep the filling from coming out; but, as the tire bears on the paper and not on the disks, the wheel partakes of the elasticity of the former.

Biela's Comet.—Arago, to quiet all apprehensions of a collision of the earth with Biela's comet, made an accurate calculation of its orbit and periods, and so showed that such a catastrophe could not occur for thousands or even millions of years. But, as Prof. Daniel Kirk wood shows, in the Journal of the Franklin Institute, the break-up of that comet, which was observed in January, 1846, very materially alters the conditions of the problem, and now Prof. Kirkwood announces the latter end of November, 1892, as the time when, in all probability the earth and the comet will come in collision. The comet's period is about six years and eight months. After the break-up of January, 1846, it reappearance in 1852 was looked for with great interest, and it was then seen that its two fragments had not only remained apart, during the interval, but that the distance between them had increased. In 1859 no observation could be taken, and in 1866, though the circumstances were eminently favorable, no comet was seen. The same thing occurred again in September, 1872. But, when the earth's orbit, on November 29th, intersected that of the comet a few weeks later, after the passage of the latter, it was expected that we should have a view of the meteors forming its dispersed train. And such was the fact, as the records of astronomical observation all over the world show. "As the meteors of this cluster," concludes Prof. Kirkwood, "are doubtless the débris of Biela's comet, if we find the epoch at which the original body would have crossed the earth's orbit near the 29th of November, we may regard the collision of our planet with some of the large fragments—and hence a grand meteoric display—as highly probable at the same period. An easy calculation, which need not here be repeated, gives the last of November, 1892, as such an epoch."

Temperature in Disease.—In health the temperature of the human body is but slightly variable, rarely oscillating beyond one or two degrees on either side of 99° Fahr. In disease, however, the variations are greater, and in the disorders of young children wider even than in those of the adult. The temperature in grown persons has been observed to fall to 95° Fahr., and to rise as high as 107° Fahr., giving a range of 12°; and these are regarded as the extreme limits of variation in the ailments of adult age. In the sickness of children, according to M. Roger, the temperature sometimes falls to 74.3° Fahr., and may rise to 108.5° Fahr., which is equivalent to a range of 33.2°. In the typhoid fever of infants, the temperature in the majority of cases attains or passes 104° Fahr. Of the eruptive fevers, it rises highest in scarlatina, sometimes reaching 105.8° Fahr., next highest in small-pox, and in measles the least of all.

Among the diseases characterized by a fall of temperature below the normal standard, Roger observed in six cases that the mercury sank to 78.8°; in other cases the depression reached respectively 77°, 73.4°, 72.5°, and in one instance to 71.6°, or 27.4° below the temperature of health.

Hansen's Writing-Ball.—Under the title of "A New Writing-Machine," we alluded in a former number to the character of this invention, which during the past season has elicited a great deal of admiration both in the Copenhagen Exhibition and in London. Since first introduced to the public, it has been very materially improved, and now not only furnishes superior facilities for writing, but is admirably adapted to the purposes of copying as well. In the improved machine, the paper rests on a level surface, so that the operator is at all times able to see what he writes, and less time is lost in adjusting and removing the sheet. By interposing carbonized paper between the sheets, and making all move together, several copies may be written or printed off at a single operation. It will thus perform the duty of several copying-clerks, and has also been found admirably suited to the work of writing out telegraphic dispatches.

Mental Labor and Health.—The Lancet reverts to the question of mental labor and longevity, in order to correct some misapprehensions of its recent articles on that topic. "Intellectual activity," persists the Lancet, "is a preserver rather than a destroyer of nervous health: but this holds true only when the conditions of ordinary hygiene are not outrageously violated." If, coupled with the intellectual strain, we have harassing anxiety, sleeplessness will result, and this is fatal. But suppose there is no such anxiety, but merely ardor for work, then a man might easily transgress the plainest laws of health. The minimum of sleep required by the adult male in twenty-four hours, according to the Lancet, is six hours, and by the adult female, seven. As for night-work, the Lancet does not think it injurious per se. The light should be very white, powerful, and steady, otherwise there will be brain-irritation. The intellectual worker must obey implicitly the reversed scriptural law: "If a man will not eat, neither shall he work." He must take abundant nutriment, at proper times, together with a "moderate amount of stimulants," says the Lancet. But any excess of alcohol or tobacco will produce insomnia: indeed, hundreds of cases where insomnia is charged to the account of "overwork" are best explained by excess in stimulation.

Dredging on the New-England Coast..—Prof. Verrill has a very interesting article in the January number of the American Journal of Science on the "Results of recent dredging expeditions on the coast of New England." In the summer of 1872 the headquarters of Prof. Baird, United States Fish Commissioner, were at Eastport, on the coast of Maine, and he invited the coöperation of Prof. Verrill and others in the work of making a thorough zoological survey of the waters of that region. Prof. Verrill had already devoted portions of six summers to the same work. The survey of 1872 not only carefully explored all the bays and estuaries, but also the deeper waters in their vicinity, more especially places known to be the haunts of valuable fishes; and the alcoholic collection of specimens obtained filled 2,000 bottles and jars, and several large cases.

Whenever animals were found to change in form or appearance on being preserved in alcohol, drawings were carefully made from life by Mr. J. H. Emerton, of Salem. The surveying party also studied and ascertained as far as possible the haunts and habits of such animals as form the natural food of fishes. The abundance and variety of living forms in the localities explored will be obvious from the statement that, besides Foraminifera, Entomostraca, and other minute creatures, the results of this and of previous dredgings, which have not been reported, add 350 species to the already known fauna of the region. Of these species some are undescribed, but the majority occur in the fauna of Northern Europe.

Marine plants were found growing at depths varying from shore-line to 80 fathoms: thus Ptilota serrata occurred at a depth of 75 fathoms. On St. George's Bank, in 430 fathoms water, 44 species of animals were obtained, not reckoning foraminifera. This is the deepest dredging yet done on our coasts north of Florida. The following were the temperatures here observed:

Air

66°

Fahr.

Surface water

65°

"

Bottom water

51°

"

Prof. Verrill, however, thinks there may have been an error in the statement of the deep-sea temperature here, owing to defects in the instruments employed. He notes, at no great distance from St. George's Bank, the following temperatures for 50 fathoms water:

Surface water

62°

Fahr.

Bottom water

45°

"

And off Cape Sable a still greater coldness of the bottom was observed in 45 fathoms water, viz.:

Air

58°

Fahr.

Surface water

56°

"

Bottom water

35°

"

In these cold waters the animal life found was more arctic in its character.

Between St. George's Bank and Nova Scotia the bottom was found to consist of fine soft, sandy mud. This, according to Prof. Verrill, may be owing to a depression of the area between the bank and the coast. This depression would withdraw the bottom out of the reach of the powerful currents which sweep over and outside the banks. Where these currents have full play, nothing but coarse sand and gravel is found even at a depth of 430 fathoms—nearly half a mile.

So strong are the currents, and so enormous their volume, in this part of the ocean, that to the east of St. George's Bank, where no bottom was found at 1,800 fathoms (rather more than two miles) depth, their mutual collision sufficed to produce a roar like breakers on a beach. The report is to be continued, and a complete list published of all the species of animals obtained.

Ostracism of a French Savant..—The new edition of Robin and Littré's great "Dictionary of Medicine" was lately presented to the French Academy of Sciences. Pathology is there regarded as a branch of biology, levying contributions on mathematics, chemistry, physics, and even social science and history. The Bishop of Orleans says that this dictionary lowers man to the level of the brutes; and the conservative justices of the peace of the sixth arrondissement of Paris take up the strain. These wise judges declare M. Robin to be incapacitated, by his religious belief, from serving on a jury. They used to order such things better than this in France, but just at present there is an effervescence of emotional religionism in that country, and, as M. Robin is not in sympathy with it, he must be put down. The disqualified doctor is one of the foremost medico-legal authorities in Europe, and can well smile at the pettishness of the justices and their backers.

Causes of Horse-Influenza.—Prof. James Law contributes to the Lens a highly-important paper on "The Causes of Influenza in Horses." This is by far the ablest study on the subject which has yet been published, and we earnestly advise those of our readers who take an interest in the matter to procure the January number of the Lens, and peruse the discussion in full. We have space only for a brief summary. The author considers, one by one, the various causes assigned both by men of science and by empirics, for the outbreak and propagation of the disease. As regards the influence of soil and elevation, he finds that these cannot be proved factors in the problem, since the mountains of Vermont and New Hampshire were visited by the epizoötic no less than the flat and malarious sea-coast of New Jersey, Maryland, and Virginia. Again, it has been supposed that a low temperature is an active agent in aggravating the disorder; but Fulton County, Ga, showed a mortality threefold greater than that of Dodge County, Wis. And yet, after the outbreak of the disorder, in the last-named locality, there occurred a great and sudden fall of the thermometer. The author shows very clearly indeed that sudden changes of weather are not the cause of the outbreak, from the meteorological tables of Toronto, where the equine influenza first appeared. These tables show that during September, 1872 (the month of the outbreak), there was the average barometer and thermometer, and that the relative humidity of the atmosphere and the direction and velocity of the wind were normal.

Another cause often assigned is acrid or fetid fogs. But, in this respect, the month of September, 1872, showed nothing peculiar. With regard to the amount of ozone in the air, the author had no estimates; but he shows that, even were that gas proved to be in excess in September, it cannot be regarded as the cause of the rise or spread of the disease. His facts on this point are entirely conclusive.

He next considers what influence is to be attributed to the action of electrical disturbance. It is certain that September, 1872, was, at Toronto, marked by a high degree of electrical disturbance. But then was that the cause of the outbreak? That is by no means proved. If it were the cause, then we should have influenza at all periods of great electrical disturbance, which is not the case. The author is, however, disposed to allow that this disturbance may have "predisposed the system to the attack of a poison which existed previously."

There remains the theory of contagion, and this the author adopts. The contagion in this case is specific, confined to one species. Breaking out first in Toronto, it radiated in all directions, following the great routes of travel, and its progress is in nearly every instance traceable to the importation of animals from infected districts. But what is the nature of the contagion here—of the diseased or morbific matter transmitted from one animal to another? On this point there are two theories. One of these holds that the specific poison consists of fungi or the like. The other, which is that of our author, sees in the granules, existing abundantly in the diseased organs, the morbific agent. These multiply very rapidly, and are conveyed to a considerable distance through the atmosphere, in the clothing of human beings, etc.

The first-named theory, that which attributes the origin and propagation of influenza to vegetal organisms, is adopted by Mr. G. W. Morehouse, in the American Naturalist. He found in the matter from a diseased horse's nostrils, and also in the air, the spores of three different cryptogamous plants, of which he gives engravings. But he fails to tell us whether or no these same spores were in the air long before or after the disorder, as well as during its prevalence. Also whether these vegetal organisms are not equally to be found in the mucous discharges of sound horses. On this point, however, we are not left to conjecture, for we have the authority of Prof. Law, corroborated by the observations of Dr. Woodward, for the statement that no "specific vegetal germs have been found in the air, blood, 05 nasal discharges, during the prevalence of the influenza."

Elevation and Subsidence of the Earth's Surface.—The Philosophical Magazine for December, 1872, contains an interesting paper by Captain F. W. Hutton, F.G.S., "On the Phenomena of Elevation and Subsidence of the Surface of the Earth," from which we condense the following: Assuming the increase of heat of the earth's interior to be 1° Fahr. to every 50 feet of descent, there occurs at a depth of about 23 miles an isogeothermal line or surface where cohesion of the rocks is overcome by heat, or rather would be so overcome at the ordinary atmospheric pressure. But the expansive force of the heat is balanced by the pressure of 23 miles of superincumbent rock, and thus a general equilibrium is maintained. The position of the earth's surface is due to three causes: 1. Its own weight; 2. Support of the interior mass; and, 3. Lateral thrust of the various portions against one another.

Whatever disturbs this adjustment must produce change of surface. If any elevation takes place in one section, there must follow subsidence in another. A great decrease of pressure is, doubtless, brought about by the radiation of heat into space, but this the author insists does not account for all the phenomena. There are two and only two agencies constantly at work, adequate to the production of this rise and fall of surface, and these are denudation and deposition, the latter being of greatest importance. The isogeothermal line will conform itself to undulations of the surface; so that, if a deposition of 100 feet of sand or rock occur, the line of heat will rise 100 feet, and the heat of the former line will correspondingly increase. Citing experiments of Colonel Totten and Mr. Adie illustrating the expansion of rocks by heat, the author says: "If the overlying mass be of loose particles, or sand, there could only be such elevation as would arise from increase of volume; but in case of solid rock, as limestone, there would be not only the increase of volume, but an arch-like elevation arising from lateral thrust. From this cause would arise ridges of elevation."

In illustration of this, he refers to the well-known elevation of the Wealden and Chalk of England. Here, with a thickness of the Cretaceous of 2,100 feet and of the Wealden of 1,300 feet, making in all 3,400 feet, we have a total rise of the arch of about 4,100 feet, the total breadth being about 100 miles. The elevation of the nummulitic limestone of the Eocene is also cited. This formation, 8,000 feet thick, is an ocean-deposit extending from Spain and Morocco to China and India, and has been elevated into enormous ridges, as the Atlas, Pyrenees, Apennines, and Himalayas. The author suggests that the cooling of mountain elevations as they rise above the snow-line may reduce the temperature of the surface, so that the rise of the isogeothermal is arrested, and further elevation ceases. On this point tables are given, showing the rise due to certain depths and areas of deposit.

Denudation, like cooling of surface, is supposed to induce subsidence in a given area by causing the line of heat to recede. But what could have disturbed the original equilibrium? "There can, I think, be but one answer to this question, viz., the origin of life on the globe. This life, by abstracting the carbonate of lime from solution in the sea, and depositing it on the bottom, first disturbed the equilibrium." The writer quotes freely from the statements of Babbage, Herschel, Croll, Hopkins, and others, to fortify points of this ingenious but perhaps in some respects fanciful hypothesis.

A Poison-Proof Bird.—A correspondent of Science Gossip tells of an attempt to capture a specimen of the scavenger-bird, or "adjutant," of India, in which he failed in a most unexpected way. On account of its valuable services in clearing the streets of decaying and putrid matter, the bird is held in high esteem by the natives, who take every precaution to protect it from harm. This prevented an open attack, and poison was the only alternative. The carcass of a partially-dissected bat was stuffed with enough arsenical paste and corrosive sublimate to kill twenty men, and the titbit thrown to a flock of the birds near by. One of them swallowed the whole of it at a gulp, and our student in comparative anatomy thought his game secure. But, though closely watched for three hours, not the slightest sign of uneasiness was manifested, and at the end of this time the creature flew away with its fellows, apparently as well as the best of them. The accustomed haunts of the flock were afterward carefully searched, but no trace could be found of the dead body wanted; and it was concluded that, unlike other gormands, this one was not to be easily got at through his stomach.

Purpose of the Rattlesnake's Rattle.—In the American Naturalist, for February, Prof. Samuel Aughey gives the results of his observations upon the use made of their rattles by the rattlesnake. It is the vulgar opinion that the reptile sounds his rattle for the purpose of enticing birds, and some naturalists even are disposed to find here a mimicry of the sound made by the so-called locust, or cicada. Prof. Aughey does not undertake to explain all the purposes served by the rattle, but he fully agrees with Mr. F. W. Putnam in rejecting this mimetic theory. Does the rattle, then, serve any useful purpose? In reply to this question, the author tells us what he has himself observed. In July, 1869, he was in Wayne County, Nebraska, and, as he was one day investigating the natural history of that district, he heard the familiar rattle of the snake. The sound was repeated at intervals, and proceeded from a rattlesnake that was calling its mate, which soon came in answer to the summons. Prof. Aughey had a similar experience the following year, and from these facts he is disposed to think that the purpose served by the rattle is to call the sexes together.

Another purpose may be to paralyze its victims with fright, and to inspire its natural enemies with terror. As an illustration of the use of the rattle for the former purpose, the author says that, as he followed through the woods of Dakota County, Nebraska, a Baltimore oriole, he heard a rattle, and at once saw the bird as it were paralyzed with fear, and ready to fall a prey to the serpent. The writer shot the rattlesnake. He adds that he once witnessed an attack of seven hogs on a rattlesnake. Soon after the battle opened, the snake rattled, and three others came to his aid. But the hogs were victorious in a few minutes.